1. Field of the Invention
The present invention relates to a paper sheet feeder device usually incorporated into a printer and more particularly, a paper sheet feeder device capable of feeding paper sheets one by one from a stack of paper sheets received on it.
2. Description of the Related Art
Printers, facsimiles, copying machines are usually well-known to print letters and images on paper sheets by electrophotographic process. These machines include a device for feeding paper sheets one by one from a stack of paper sheets mounted at a certain position on it.
A conventional paper sheet feeder device 10 shown in FIG. 1 includes a feeder roller 11 and a paper sheet mounted plate 30. A rear end 30B of the paper sheet mounted plate 30 is swingably supported round a pin 31 and a front end 30T thereof is urged against the feeder roller 11 by a spring 39. Further, the paper sheet feeder device 10 includes a paper sheet separator mechanism 15 comprising a holder member 16 swingably supported by a rod 19, a paper sheet separator pad 17 made by cork and bonded on the top of the holder member 16, and a spring 18 for urging the paper sheet separator pad 17 against the feeder roller 11.
When the feeder roller 11 is rotated while keeping a stack of paper sheets mounted on the plate 30, a top sheet of paper is picked up by the feeder roller 11 and fed to a paper sheet conveyer system 70 through a point Q. When the forward edge of the paper sheet is nipped between the rollers 71 ad 72, the sheet is further conveyed in a direction X as the rollers 71 and 72 are rotated. The sheet is then conveyed to a printing position (not shown) by the paper sheet conveyer system 70. The paper sheet separator mechanism 15 serves to separate a sheet of paper from two or more entering between the feeder roller 11 and the pad 17.
A cover 50 serves to selectively cover an opening 2 formed in a side of the printer apparatus and it can swing into a housing 1 of the printer apparatus round a rod 51 by which its rear end is supported. It opens the opening 2 as shown by a solid line and closes it as shown by a dot and dash line. When a stack of paper sheets is mounted on the plate 30 through the opening 2, rear ends of these paper sheets are supported by the cover 50.
When a stack of paper sheets is to be mounted on the plate 30, front end portion of these paper sheets must be sandwiched between the feeder roller 11 and the plate 30. To achieve this, the plate 30 is pushed down against the spring 39 by one hand while the stacked paper sheets are mounted on the plate 30 by the other hand.
The paper sheet feeder device 10 shown in FIG. 1, however, has the following drawbacks.
A stack of paper sheets must be supplied while pushing down the plate 30 by one hand. If the plate 30 is pushed down to an excessive level, too many paper sheets are mounted on the plate 30, as shown in FIG. 10B. An angle .theta. at which the stacked paper sheets enter onto the separator pad 17 becomes larger as the stacked paper sheets become higher. As the angle .theta. becomes larger, therefore, paper sheets are more likely to stay at a position where their front end portions contact the pad 17. This causes sheet jamming in the printer apparatus. Further, if one hand is released from the plate 30 when the mounting of the stacked paper sheets is not finished on the plate 30 yet, the plate 30 is rapidly sprung up by the spring 39. Excessive shock is thus added to an actuator for the paper sheet detector, and other components, thereby causing them to be broken. To avoid this, a careful work must be needed but this causes quick paper sheet supply to be disturbed.